Couple things - since it’s a Thinkpad, it’d be hard not to mention that they come with a full hardware maintenance manual, full of FRUs and how to do full teardowns. You don’t even need a third party guide.
You’d also be remiss in not exploring the open source Coreboot/Libreboot UEFI replacements.
I also have a feeling that the ‘approved card list’ has more to do with FCC certification than any particular proprietary shenanigans… but that’s just a feeling.